Bathing vessels may be manufactured from a variety of different materials, such as plastic materials. Plastic bathing vessels, however, must meet certain minimum performance requirements. For instance, the American National Standards Institute (ANSI) sets forth minimum physical requirements and testing methods for plastic bathtub and shower units. A bathing vessel that meets the requirements is approved for use in homes, buildings or other structures as a plumbing fixture.
Therapy bathing vessels commonly referred to as air tubs and whirlpools, use piping through with the air and/or water is moved to provide a massaging experience for which they are known. Therapy tubs are typically manufactured using a thermoformed surface layer backed with thermoset polyester that is reinforced with fiber glass. This method of construction has been in practice for many years. The bathing vessel is manufactured and holes are then drilled in locations into the piping for the water to feed the pump and the water and/or air to enter the bath.
The water and/or air is moved through external piping that is connected from the pipe or blower to the holes in the bathing vessel. A more recent method utilizes channels that are incorporated into the structure of the bathing vessel and are encapsulated within the polyester reinforcing composite material.